In conventional Winchester disk drives, a read/write head or transducer assembly "flies" upon an air bearing or cushion in very close proximity to the rotating surface of the data storage disk. The disk surface carries a thin film magnetic material having a multiplicity of magnetic storage domains that may be recorded and read back by the head. The transducer assembly, which can be any conventional combination of transducers, sliders and load beams, is positioned and supported proximate the surface of the data storage disk using an actuator. The combination of the transducer assembly and the actuator is known as the transducer actuator or actuator assembly. The actuator supports the load beams and sliders and accurately positions the transducers above the surface of the disk within a "data area" to read and write data from/to the disk. When not in operation, the actuator assembly remains stationary in a "landing zone" along the inner diameter of the disk wherein the transducer rests on the surface of the disk. An actuator latch prevents the actuator assembly from moving into the data area during non-operation. The latch may include an air vane portion which extends over the surface of the disk and pivots about an axis of rotation. As airflow generated by the rotating disk overcomes a biasing force from e.g. a magnet, the latch moves to release the actuator assembly. Such actuator latches are known as "airlocks".
Hard disk drives (HDD's) have typically used textured media having a moderate coefficient of friction of less than 1.0 between the read/write heads and the disks. If the actuator latch on such an HDD were to fail, resulting in the head being in contact with the data area of a stationary disk, this moderate coefficient of friction was low enough that the spindle motor typically could start. Thus, although the latch failure could result in media damage and possibly some data loss, it would not typically result in a catastrophic drive failure such as the inability to spin up.
In the quest for higher and higher areal densities, the industry is increasingly adopting "zone-textured" media. With this media, only the landing zone is textured, and has a coefficient of friction typically less than 1.0. The data area is smoothly polished, and the coefficient of friction therein may be 10 or more times higher than that in the landing zone. Failure of the actuator latch in a drive employing such media would likely result in catastrophic drive failure. Thus the advent of zone-textured media has made the reliability of actuator latches much more important than it has been in the past.
FIG. 1 shows a plan view of a somewhat simplified disk drive 10 incorporating an airlock actuator latch 11. The airlock actuator latch 11 includes an air vane portion 12, depicted in a latched position, wherein the transducer 4 rests on a disk 13 at a landing zone 2. As shown in FIG. 1, in order for a transducer 4 to enter a data area 3 of the disk 13, airlock actuator latch 11 must rotate clockwise, to disengage from an actuator assembly 17, followed by a clockwise rotation of the actuator assembly 17.
The latch 11 is specifically designed to be mass balanced about its axis of rotation so that linear shocks will not cause it to rotate and possibly permit the actuator assembly 17 to escape from its latched position. In practice, conventional rotary airlock actuator latches have proven to be reasonably reliable in keeping the actuator assembly 17 latched, provided that the input shock is linear in nature.
However, conventional air vane actuator latching mechanisms such as that of FIG. 1 offer less protection against rotary shock forces. When subjected to rotary shock, which may be described as sudden and rapid rotational movement of the disk drive 10, the respective inertias of the air vane latch 11 and the actuator assembly 17 cause them to tend to maintain their relative angular orientation, rather than to rotate with disk drive base 18. Thus, if the base 18 is suddenly rotated counterclockwise, the air vane latch 11 and the actuator 17, will tend not to rotate with the base 18. In effect, the latch 11 and actuator 17 undergo a clockwise rotation with respect to the base 18, resulting in the orientation shown in FIG. 2 and an unwanted release of the actuator assembly 17. When the disk 13 is not rotating, release of actuator 17 causes unwanted contact between the slider and the data storage area 3. (FIG. 2 shows this problem) In practice, it is fairly easy to cause the prior air vane latch to fail in response to certain rotary shock forces, more frequently present especially in portable and laptop computers.
Thus, there exits a hitherto unsolved need for an improved, simple and cost efficient latching apparatus which can effectively protect against rotary as well as linear shock forces.